The inkjet recording method is abruptly overspread and still making a progress, because the material cost is low, high-speed recording can be performed, noises are less generated at the recording and color recording is facilitated.
The inkjet recording method includes a continuous system of continuously jetting out a liquid droplet and an on-demand system of jetting out a liquid droplet according to image information signals, and the ejection system therefor includes a system of ejecting a liquid droplet by applying a pressure from a piezoelectric element, a system of ejecting a liquid droplet by generating a bubble in an ink under heat, a system using an ultrasonic wave, and a system of ejecting a liquid droplet by suction using an electrostatic force. As for the inkjet recording ink, an aqueous ink, an oil-based ink or a solid (fusion-type) ink is used.
The coloring agent used in such an inkjet recording ink is required to exhibit good solubility or dispersibility in a solvent, enable high-density recording, provide good color hue, be fast to light, heat and active gases in the environment (for example, oxidative gas (e.g., NOx, ozone) and SOx) and highly resistant against water and chemicals, ensure good fixing property and less blurring on an image-receiving material, give an ink having excellent storability, have high purity and no toxicity and be available at a low cost. However, it is very difficult to find out a coloring agent satisfying these requirements in a high level.
JP-A-52-76331 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) describes a water-soluble disazo dye having a heterocyclic ring, but when an ink is prepared by using this water-soluble disazo dye, the ink is insufficient in the storage stability. An ink having excellent storage stability and fastness to oxidative gas such as ozone is keenly demanded.